Bleach-out process of color photography.



I Ito Drawing.

JOHN HEuRY SMITH, orzunron, SWITZERLAND, AND .WALDEMAR vrnncxnns, or

' MuL AUsEN, GERMANY;

BLEACH-our :rnocnss or oo on PHOTOGRAPHY.

Specification of Letters Patent. Patented J an. 2,1912. Application'filed January 26, 1907, Serial No. 354,237. i

' To all whom it may concern; 1

Be it known that we, JOHNIIENRY SMIrH, a subject of the King of Great Britain, residing in Zurich, in the Canton of Zurich,

Republic of Switzerland,- whose post oflice address. is No. 417 Seestrasse, Zurich, and 'VlZALDEMAR MnRonnNs, a subject of Germany,xresiding in Miilhausen, Elsass, Germany, whose post-ofiice address is No. 1 Schwarzwaldplatz,- Miilhausen, have invented certain new and useful Improvements in the Bleach-Out Process' of Color Photography; and we do hereby' declare the fol-- lowingto be a full, clear, and exact description-of the invention, such as will enable others skilled in the art to which it appertains to makeand use the' san1e..

We have applied for patent in Germany on February 2nd 1906,'Application S.- 22257 VI/57". g

In the course of experiments'f for the'p'roduction of bleach-out sensitive surfaces we found that a-regularity exists in regard to the wandering of dyes from a coating of one medium intothat of another," more especially from gelatin into'collodion e. the

basic colors auramin and 'methylene blue wander into the collodion film, and the resulting papers on examination show a green collodion film underneath a red gelatin film. If'a mixture of the same dyes in collodion is coated upon a gelatinbase, the erythrosin wanders into the gelatin leaving a green collodion film upon a red gelatin film. If, in stead of these colors, fiavanilin (basic) and.

flavanilin S (acid) be employed, the former gives the same result as auramin, whereas fiavanilin-S wanders into the gelatin as coated .upon a gelatin base yields an orange ry hmsill did. A mixture offlavanilin S,

erythrosin and methylene blue in collodion coloredgelatinfilm upon a blue collodion film ii however in place of methylene blue basic dyes would occur.

bleach-out process. To coat several layers an "acid blue dye e. g. naphthyl blue'2 B be coated in collodion upongel'atim'a colored gelatin film underneath a colorless collodion methylene blue are employed in'whichever t5 l'nediulnthey are mixed and coated colored collodion and colorless gelatin are the result. If the basic dyes are coated in' a gelatin solution upon a gelatin base,un'derneath wvhich is a collodion film, the basic dyes will; 60

wander through the gelatin base even should this be colored with one or more acid dyes into the collodion film; the acid dyes behave similarly inasmuch as they will :wander through a collodion layer to find their state ofrest-in a gelatin film. 1

Inthe reparation of bleach-out paper,,it' I I I has been usual, in many cases, to employ both acid and basic dyes together. However, it is not possible to coat an emulsion containing both ,acid and basiod'yes direct 'upon' a paper support, in such manner that all the dyes remain'in the emulsion film; in

every case, the dyes separate more or less. I l

This separation is unavoidable because otherwlse, areactlon between the acld and It is exceedingly difiicult to coat with.

ordinary coating machinery-a solution containing one or more dyes, as the slightest difference in the thickness ofcoating, which would not be observed in the caseof silver bromid paper or plates, Will form'streaks which mustbe altogether avoided in the p of differently colored dye solutions one upon another so that an evenly colored harmonious surface results is almost impossible,

the faults are increased in each successive coating so that one or other of the colors is in preponderance. This difliculty ofcoating a second film of color emulsion may however be entirely overcome by the utilization, of the principle of wandering, inasmuch as the acid or basic dyes are giventhe' opportunity to wander. into a state of rest.

The second coating can thus be dispensed withas the separation of the-{dyes takes the wandering of the dyes.

so that under the conditions which obtained.

, in thosegexperin'ients the dyes not only wandered into the collodionbasebut also into 7 the tissue of the paper. If a coating of gelatin, glue, etc., between the collodion base and the paper surface had be'eii employed a satisfactory result would have beenobtained.

The experiment-er never sawf in the fact of some dyes wandering that certain technical advantages could be obtained. He sought rather to prevent the wandering-from occurringand en this account was not successful in preparing ableach-out p'apcr: although it wouldhaye been. possible for him to have preventedjthe wandering. altogether by coat ing thefpaper with a preliminary solution of resin or lac: The publication of the negative results obtained from the experimenter can'ne ver collide with our invention, more especiallyas-we have-shown above that the experimenter had not the slightest acquaintance with the nature of the principle of wandering. and rather looked upon the wandering ,itself as a distinct technical disadvantage. v I

. Othertechnical advantages pertaining to the application of the wandering principle may he mentioned In cases where/it is necessary to obtain absolutely sharp pictures it is necessary to have all the dyes contained in one layer; this might of coursebeobtained as mentioned above by the use of' a coating of resin hr lac, but this again would be accompanied 'by other technical difficulties, such as stickiness,- slowdrying, etc. It

is much preferable .to apply the principle menlioned above of the affinity shown by the dyes to certain layers .of rest, and either coat the dyes in such a layer upon paper.

which has received a coating having no affinity to the dyes employed 1 or to coat them in a layerhaving no affinity. upon paper prepared with a coating for which the dyes-have affinity. thus allowingwthem to wander to 'their position of rest' In the case of the employment of acid dyes in gelatin solution the emulsion may be coated direct upon collodion paperjwhereas in the-case of a mixture of basic dyes, coated in gelatin solution upon collodion another gelatin coatmg would be required between the paper and the collodion film to preventthe dyes.

' entering the tissue of the paper. In the case of coating acid dyes in collodion solution upon gelatin paper no. such isolating layer is required as the dyes have a greater aiiinity to the. gelatinthan to the paper;'in the employment of basic dyes in collodion solution the emulsion may also be coated direct upon gelatin in paper asthe dyes are already in their position of rest. We have already referred to the process of obtaining two layers of diiferently colored film; it is easy to see that by this means mixtures of basic and acid dyes can be separated at will in the simplest manner, so that the dyes may bebrought orallowed. to wander in the upper or lower stratum as may be most suitablefor their being sensitized; the sensitizers being either added direct to the, emulsion layer or allowed to be absorbed by the dyes from a 'sensitizingbath into which the dyed films are subsequently placed, by which means the sensitiveness of the one layer may be increased to that ofzthe other one.

Instead of gelatin as matrix other similar .bodies 6. glue, isinglass, gum, albumen,

casein, etc, may be employed, andinstead of nitrocellulose-other cellulose derivates, e, g. cellulose acetate, etc, and other lac yielding bodies may be used.

What we claim is:

1. A process for the manufacture of bleach out surfaces,'consisting in emulsify ing a plurality of dyes in a vehicle for which they have relatively low aflinity, and coating the emulsion upon a prepared layer for which the dyes have relatively high aflinity, to allow the dyes to pass into saidlayer.

2. A; process for I the manufacture of bleach out surfaces, consisting, in emulsifying a plurality of basic dyes in a vehiclefor which they have relatively low aliinitv. and coating the emulsion upona prepared layer for which the dyes have relatively highaifinity, to allow the dyes-to pass into said layer 1 f 3. A process for the manufacture of bleach out surfaces. consisting in emulsifying a pluralityvof dyes in avgelatinous vehi-- cle for which they have relatively low afiinity. and coating the emulsion upon a pre pared layer for-which the dyes have relatively high affinity, to allow the dyes to pass into said layer.

4. A process for the manufacture of bleach out surfaces. consisting in emulsifying a plurality of dyes in a vehicle for which they have relatively low affinity, and coating the emulsion upon'a prepared nitrocellulose layer for which the dyes have relativelv hi 2h ailinit-y, to allow the dyes to pass into said layer.

7 ing a plurality of dyes in a vehicle for which they have relatively low afllnity, andcoating the emulsion upon a'prepa-red layer of nitrocellulose mounted upon paper and for whi h prepared layer the dyes have relatively high afiinity, to allow the dyes to pass into said prepared layer.

In testimony whereof, we have signed our nemes to this specification in the presenee of two subscrlbmg wltnesses.

JOHN HENRY SMITH. WALDEMAR MEROKENS.

Witnesses HERMANN HUBER, JOSEPH SIMON. 

